A covering material of this type is disclosed in Netherlands Patent Application 8402655. The known material consists of a suspension of, for example, cellulose waste (paper) as filler, carboxymethylcellulose or polyvinyl acetate as binder and, in addition, a light-absorbent agent, such as soot, and inhibits the growth of grasses.
According to Swiss Patent 678478, ground in parks and gardens can be protected against weeds by applying a layer of material consisting of felted paper residues, optionally mixed with polystyrene foam. Netherlands patents 91383 and 98116 teach the use of hydroxyalkyl and carboxymethyl starches and swelling starch, respectively, for protecting soil against erosion.
However, the protective effect of the known covering materials is of relatively short duration. Furthermore, these materials also contain poorly degradable constituents (polyvinyl acetate, polystyrene) and mould formation often takes place in the material in the course of time.